Radome structures are conventionally used to protect microwave antennas from the physical environment. It is also desirable to shield such equipment from externally incident electromagnetic energy which can adversely affect the electrical operating characteristics thereof. Ideally, such a shield during operation of the antenna equipment should be transparent to the energy in a selected frequency range handled by the antenna (the "in-band" frequency range) but should reject all frequencies outside such frequency range (the "out-of-band" frequency range). Further, when the antenna equipment is not operating, such a shield should reject electromagnetic energy over all frequencies of concern.
Radome shields having such characteristics have often been referred to as "shutter-type" radomes, the frequency shutter in effect being effectively "closed" to all frequencies during non-operation and the frequency shutter being effectively "opened" only to the desired operating frequency band during operation. Shutter-type radomes presently used in the art have consisted primarily of electro-mechanical devices which are relatively bulky and cumbersome to fabricate and use and which have the added disadvantage of being relatively slow in changing from one mode of operation to the other. It is desirable to develop simpler structures for such purpose which structures can provide relatively fast operation shifting from the "shutter open" to the "shutter closed" states.